Furnace construction



Oct. 1, 1963 H. w. LUCAS 3,

FURNACE CONSTRUCTION Filed June 14, 1961 2 Shets-Sheet IL I Oct. 1, 1963 w. LucAs 3,105,485

FURNACE CONSTRUCTION Filed June 14, 1961 2 Sheets-Sheet 2 United States Patent 3,105,485 FURNACE CGNSTRUCTION Harry William Lucas, Rexdale, Ontario, Canada, assignor to The Coieman Company, Inc., Wichita, Kane, a corporation of Kansas Filed June 14, 1961, Ser. No. 117,016 4 Claims. (Cl. 126-116) This invention relates to furnace construction and, in particular, to a mounting arrangement for a heat exchanger within the casing of a domestic heating furnace.

In furnaces, as presently constructed, the differential expansion between the heat exchanger which, during the operation of the furnace, becomes very hot and the easing, which during the operation of the furnace, may remain relatively cool, has been unsuccessfully accommodated. The relative expansion and contraction impose serious stresses upon both the heat exchanger and upon the casing with the result that bending, warping and other deformation of the structure may result. Even in the absence of such permanent damage the relative expansion and contraction causes loud cracking and straining noises in the furnace which, of course, are undesirable to the householder in whose home the furnace is installed.

It is an object of the present invention to provide sup port structure for a heat exchanger within a furnace casing which will permit relative expansion and contraction of the heat exchanger and the casing to take place without imposing such stresses upon either member and, accordingly, which will eliminate the undesirable damage and noise which is commonly caused by furnaces constructed in accordance with conventional practice.

The invention is described by way of example in the following specification and illustrated in the accompanying drawings which show a preferred embodiment of the invention and in which like reference numerals refer to like parts in the various views and in which:

FIGURE 1 is a side elevation of a furnace with parts of the casing cut away to show the internal construction;

FIGURE 2 is an enlarged cutaway perspective view of a portion of FIGURE 1; and

FIGURE 3 is a still further enlarged view of the subject matter of FIGURE 2 with several of the parts in exploded position.

Referring now to FIGURE 1, it will be seen that the furnace generally comprises an outer casing which may conveniently be of sheet metal and which is internally provided with strengthening spars and braces as may be found expedient for the particular design of the furnace in association with which it is used. The spars and braces of the casing form no part of the present invention and will therefore not be described except where they are directly connected to portions of the structure with which the invention is concerned.

Extending across the casing in a horizontal direction is a first partition 11 which is conveniently supported and secured in place by conventional means. Below this partition 11 there is provided a blower 12 driven by an electric motor 13 the purpose of which is to pass air to be heated over the external surface of a heat exchanger 14. The air to be heated enters the lower portion of the easing through an entry port which is not shown but which is constructed and located in accordance with conventional practice. The air to be heated passes upwardly over the surfaces of the heat exchanger 14 and is discharged into the distribution ducts of the heating system through the outlet port '15 let in the top wall of the casing 10.

The heat exchanger =14 is mounted in the casing 10 by means of a first support A which includes a downwardly extending flange 16 on the lower forward edge of 3,ih5, i Patented Get. 1, 1963 the heat exchanger which is bolted to a vertical partition wall 17 which is a part of the casing 10, by means of bolts :18. Washers 16a lie between the flange 16 and the wall 17 about the bolts 18. Thus, at the location of the first support A, the heat exchanger '14 is rigidly secured to the casing 19 and the relative positions of the heat exchanger 14 and the casing 10 remain unchanged at this point.

A second support B for the heat exchanger 1-4 is provided by means of the member 19 which extends upwardly from the partition 11 and constitutes a rest upon which the rearward lower edge of the heat exchanger 14 may bear due to gravity. No other mechanical connection between the heat exchanger 14 and the member '19 need be provided since, as the heat exchanger expands it will move rearwardly relative to the support A and the lower surface of the heat exchanger 14 may therefore slide upon the rest \1'9 and so accommodate expansion of the heat exchanger in this direction.

If necessary, or if desirable, the support B may be dispensed with and the strength of the support A must, accordingly, be increased so as to support the heat exchanger in position without the necessity of providing an additional support B. Alternatively, the nature or character of the support A may be altered and its position may be changed so that the lower end of the heat exchanger 14 may be supported in a manner other than that shown in FIGURE 1. The particular nature and character of the lower supports of the heat exchanger are relatively unimportant in detail, it merely being essential, for the operativeness of the present invention that the lower end of the heat exchanger is provided with a support which will bear the weight of the heat exchanger and which will provide means whereby the horizontal component of the expansion of the heat exchanger may be adequately accommodated without imparting undue stresses to structure associated with the casing.

In the embodiment shown in FIGURE 1 there is provided, in addition to the first support A and the second support B, a third support, indicated generally by the reference character C. This third support is illustrated in greater detail in FIGURES 2 and 3, and reference will now be made specifically to these figures for a description of this portion of the supporting structure.

Referring first to FIGURE 2, it will be seen that the upper end of the heat exchanger is provided, in the embodiment illustrated, with three openings bearing reference characters 21, 22 and 23. It is through these openings that the products of combustion may be extracted from the interior of the heat exchanger where the fuel is burned by means of the burner 24 which, as shown in FIGURE 1, extends into the interior of the heat exchanger. The burner, in the embodiment illustrated, is intended to burn either natural or other combustible gas but, of course, other types of burners may be substituted for the one shown.

The openings 21, 22 and 23 in the heat exchanger (as seen in FIGURE 3) are surrounded by a flange 2.5 which is secured to the heat exchanger and which presents a surface 26 lying in a vertical plane. The flange surrounds and defines the flue openings in the heat exchanger and is provided, at spaced points about its periphery, with a plurality of openings 27 for a purpose which will be subsequently described.

The Wall 17 extends upwardly in the casing from the first support A in front of the heat exchanger 14, as seen in FIGURES l, 2 and 3. The upper end of the partition 17 is provided with a flue opening 28 through which the products of combustion emerging from the openings 21, 22 and 23 and the heat exchanger may be extracted. -As can be seen in FIGURE 1, the opening '28 leads into a flue chamber 29 which, in turn, is provided with a flue collar 3! by means of which the furnace may be connected to a chimney so that the products of combustion may be directed outside the building into the atmosphere.

Secured to the flange which surrounds and defines the flue opening in the heat exchanger there is provided a plate, indicated generally by the reference character 31, which is rectangular in shape and which is composed of a first gasket 32, a metal plate 33, and a second gasket 34. The first gasket 32 lies between the flange 25 and the plate 33 and the second gasket 34 lies on that side of the plate 33 remote from the flange 25'. The cornposite plate 31, therefore, is secured to the flange 25 by means of bolts, rivets, screws or other suitable means which pass'through the openings 27 in the flange and also through openings 35 in the composite plate which register with openings 27'.

The flue opening 28 in the casing wall 17 is provided with vertical channel means along its vertical edges defined firstly by flanges 36 which lie parallel to the wall 17 although displaced therefrom, and second flanges 37 which are carried by brackets secured to the wall 1?. The channels 33 thereby defined on each side of the opening 28 in the casing wall 17 receive the vertical edges 39 of the plate 31 and permit sliding vertical movement of the plate 31 relative to the casing wall 17. It will be seen, accordingly, that the third support C for the heat exchanger 14- permits vertical sliding movement upwardly and downwardly relative to the casing of the upper end of the heat exchanger which, of course, will experience this movement due to the expansion and contraction of the heat exchanger during the heating cycle of the furnace.

The lower horizontal surface 40 of the plate 31 lies in overlapping relationship to the upwardly-extending flange 41a of the lower horizontal edge of the channel generally designated 41 of the opening 28 in the wall 17. In the embodiment illustrated in FIGURE 3, the lower horizontal edge of the opening 28 in the wall 17 is provided with the channel 41 similar to the channel 38 formed in the vertical edges but it is not essential that it be so provided. It is merely essential that the lower edge flange 41a; of the opening 28 in the wall 17 lie in overlapping relationship with the lower edge 41 of the plate 31 and that the overlapping between these two members he of such an extent that it is greater than the maximum displacement of the plates in a vertical direction due to expansion and contraction in the heat exchanger. Cooperating with the inner, upwardly-extending flange 41a and defining channel 41 is a flange 41b (see FIG. 3) which is provided as part of bracket 41c in the same fashion as flange 37 is provided as part of bracket 37a.

Returning now to FIGURE 2, it will be seen that the top wall 42 of the casing it) is provided, at the point where it defines the upper edge of the opening 28 in the wall 17, with a downwardly extending flange 43 which, as shown in FIGURE 2, lies in overlapping relationship with the upper edge 44.- of the plate 31. Here again, the extent of overlap must necessarily be greater than the maximum displacement of the plate 31 due to expansion and contraction of the heat exchanger and, in the cold position of the heat exchanger there must necessarily be provided a clearance or gap between the upper edge 44 of the plate 31 and the top wall 42 of the casing 10 so as to accommodate the upward movement of the plate 3 1 due to expansion of the heat exchanger 14 when it becomes hot.

Having now described the invention in detail, it is believed that the operation of the device will be clear.

When the furnace is in the cold condition and the heat exchanger 14 is at its smallest dimension, the plate 31 will occupy the lowest position within the opening 28. As the burner 24 is ignited and the heat exchanger becomes hot, it will begin to expand. Rearward expansion 4 of the heat exchanger relative to the burner 2 will be accommodated, as previously described, by the movement of the heat exchanger 14 over the upper surface of the member 19 which constitutes the second support B. Upward expansion of the heat exchanger 14 will be accommodated by the sliding of the plate 31 within the channels 38 and he relative sliding movement of the lower edge 4% of the plate 31 on the surface of the lower edge flange 41a of the opening "28 in the wall 17. The upper edge 44- of the plate 31 will slide relative to the flange 43 in the top surface 42 of the casing it By this means the expansion and contraction of the heat exchanger 14 is not transmitted to the casing 19 and, accordingly, no stress is imposed upon either the casing or the heat exchanger with the result that none of the undesirable conditions of the prior art are experienced in this construction.

in the sub-joined claims the invention is defined with reference to a flue opening in the heat exchanger'and in the casing. The flue opening in the casing to which reference is made in the claims is intended to be construed as the opening 28 in the wall 17 of the casing despite the fact that the casing lit, in the embodhnent illustrated in FiGURES l and 2, extends beyond the wall 17 and is provided with a front wall, as shown in FIGURE 2, by the reference character ltiat Chamber 29, as shown in FIGURES l and 2, is a draft diverter which is used solely to control the draft which would effect combustion and is, also, designed in such a way as to prevent the spillage of products of combustion into the room. In addition, it provides a stationary collar 30 to which the flue pipe may be secured so that the expansion and contraction of the heat exchanger will not cause flexing and movement of the flue which might otherwise be directly connected to the opening 45 in the plate 31 which opening is, of course, in registry with 21, 22, 23 in the heat exchanger 14.

Having described the invention in specific detail with reference to a preferred embodiment, it is to be pointed out that this description is to be read in an illustrative sense and that minor modifications are contemplated in the specific structure disclosed without departing from the spirit of the invention as defined in the sub-joined claims.

I claim:

1. In a furnace construction, including a casing, a heat exchanger in the casing, means to pass air to be heated over the heat exchanger through the casing, a burner for burning fuel in the heat exchanger, said heat exchanger and the adjacent vertical wall of the casing forming a flue opening in the heat exchanger and in the casing through which the products of combustion may be extracted, mounting means for the heat exchanger to avoid stresses in the heat exchanger and in the casing due to expansion and contraction of the heat exchanger relative to the casing comprising a lower support carried by the casing and rigidly fixing a point on the heat exchanger to the casing and supporting the weight of the heat exchanger and an upper support adjacent an upper edge of the heat exchanger comprising a flange lying in a vertical plane and surrounding and defining the flue opening in the heat exchanger, a rectangular plate secured to the flange, the plate having an aperture registering with the flue opening in the casing, and vertical and horizontal channel means respectively carried by the vertical and horizontal edge portions of the flue opening in the casing to hold the vertical and horizontal edges of the plate in sliding, sealing relation against the corresponding vertical and horizontal edge portions of the flue opening in the casing so that the plate may move vertically upwardly'and downwardly clue to expansion and contraction of the heat exchanger relative to the casing without imposing stresses upon either the heat exchanger or the casing.

2. In a furnace construction as claimed in claim 1, mounting means for the heat exchanger to avoid stresses in the heat exchanger and the casing due to'expansion and contraction of the heat exchanger wherein the lower support carried by the casing rigidly fixing a point -on'the enemas 5 heat exchanger to the casing comprises a first support carried by the casing and securing the heat exchanger to the casing along one lower edge, and a second support carried by the casing and providing a rest upon which the opposite lower edge of the heat exchanger may bear due to gravity.

3. In a furnace construction including a casing, a heat exchanger in the casing, .-eans to pass air to be heated over the heat exchanger through the casing, a burner for burning fuel in the heat exchanger, said heat exchanger and the adjacent vertical wall of the casing fortna ilue opening in th heat exchanger and in the casing through which the products of combustion may be extracted, mounting means for the heat exchanger to avoid stresses in the heat exchanger and in the casing due to expansion and contraction of the heat exchanger comprising .a first support carried by the casing and rigidly fixing the heat exchanger to the casing along one lower edge of the heat exchanger, a second support carried by the casing and providing a rest upon which the opposite lower edge of the heat exchanger may bear due to gravity and a third support for the heat exchanger adjacent an upper edge of the heat exchanger comprisin a flange lying in a vertical plane and surrounding and defining the lue opening in the heat exchanger, a rectangular plate secured to the flange in parallel relationship thereto, the plate having an aperture in registry with the flue opening in the heat exchanger and vertical and horizontal channel 6 means respectively carried by the vertical and horizontal edge portions of the flue opening in the casing to receive the vertical and horizontal edges of the plate in sliding, sealing relation against the corresponding vertical and horizontal edge portions of the flue opening in the casing, the horizontal channel means of the horizontal edge portions of the flue opening in the casing overlapping the piate surfaces adiacent the horizontal edges thereof by an amount greater than the maximum displacement of the plate due to expansion and contraction of the heat exchanger whereby the plate may move vertically upwardly and downwardly due to expansion and contraction relative to the casing without imposing stresses upon either the casing or the heat exchanger.

4. in a furnace construction as claimed in claim 3, mounting means for the heat exchanger wherein the third support for the heat exchanger is associated with that upper edge of the heat exchanger which lies above the lower edge secured to the casing by the first support.

Refers ices titted in the file of this patent UNITED STATES PATENTS 362,297 McDowell May 3, 1887 582,930 King May 5, 1897 2,658,504 Jaye et al Nov. 10, 1953 2,808,047 Jaye et a1. Oct. 1, 1957 2,923,349 Marble et al. Feb. 2, 1960 

1. IN A FURNACE CONSTRUCTION, INCLUDING A CASING, A HEAT EXCHANGER IN THE CASING, MEANS TO PASS AIR TO BE HEATED OVER THE HEAT EXCHANGER THROUGH THE CASING, A BURNER FOR BURING FUEL IN THE HEAT EXCHANGER, SAID HEAT EXCHANGER AND THE ADJACENT VERTICAL WALL OF THE CASING FORMING A FLUE OPENING IN THE HEAT EXCHANGER AND IN THE CASING THROUGH WHICH THE PRODUCTS OF COMBUSTION MAY BE EXTRACTED, MOUNTING MEANS FOR THE HEAT EXCHANGER TO AVOID STRESSES IN THE HEAT EXCHANGER AND IN THE CASING DUE TO EXPANSION AND CONTRACTION OF THE HEAT EXCHANGER RELATIVE TO THE CASING COMPRISING A LOWER SUPPORT CARRIED BY THE CASING AND RIGIDLY FIXING A POINT ON THE HEAT EXCHANGER TO THE CASING AND SUPPORTING ADJACENT AN UPPER EDGE OF THE HEAT AND AN UPPER SUPPORT ADJACENT AN UPPER EDGE OF THE HEAT EXCHANGER COMPRISING A FLANGE LYING IN A VERTICAL PLANE AND SURROUNDING AND DEFINING THE FLUE OPENING IN THE HEAT EXCHANGER, A RECTANGULAR PLATE SECURED TO THE FLANGE, THE PLATE HAVING AN APERTURE REGISTERING WITH THE FLUE OPENING IN THE CASING, AND VERTICAL AND HORIZONTAL CHANNEL MEANS RESPECTIVELY CARRIED BY THE VERTICAL AND HORIZONTAL EDGE PORTIONS OF THE FLUE OPENING IN THE CASING TO HOLD THE VERTICAL AND HORIZONTAL EDGES OF THE PLATE IN SLIDING, SEALING RELATEION AGAINST THE CORRESPONDING VERTICAL AND HORIZONTAL EDGE PORTIONS OF THE FLUE OPENING IN THE CASING SO THAT THE PLATE MAY MOVE VERTICALLY UPWARDLY AND DOWNWARDLY DUE TO EXPANSION AND CONTRACTION OF THE HEAT EXCHANGER RELATIVE TO THE CASING WITHOUT IMPOSING STRESSES UPON EITHER THE HEAT EXCHANGER OR THE CASING. 